Electromagnetic reciprocating motor



Dec. 7, 1965 J. A. BLOMQUIST ELECTROMAGNETIC RECIPROCATING MOTOR FiledMarch 4, 1965 IN VENTOR.

V A Nu WW w h 7 MN United States Patent Ofilice 3,222,554 Patented Dec.7, 1965 3,222,554 ELECTROMAGNETIC REQIPROCATING MOTOR John A.Blornquist, Aurora, IlL, assignor of one-half to New-Mark Builders,Inc., Aurora, Ill., a corporation of Illinois Filed Mar. 4, 1963, Ser.No. 262,572 10 Claims. (Cl. 310-35) The present invention relates toelectromagnetic rectilinear accelerators and motors, and particularly,to an improved, self-contained, A.C.D.C. electromagnetic reciprocatingmotor.

Electromagnetic rectilinear accelerators and motors are generallycomprised of a cylinder, a permeable armature slidable in the cylinderand a plurality of electromagnetic coils spaced along the cylinder andenergized sequentially in such manner as to draw or pull the armature ina given direction as the coils are energized in sequence in suchdirection. The sequential energization of the coils has heretofore beeneifected in two ways, namely, 1) by reliance upon the periodicity ofalternating current sources, involving of course auxiliary controlapparatus, and (2) by use of a switching device operated by an auxiliaryrotary motor.

The object of the present invention is to provide an improvedelectromagnetic reciprocating motor that does not require auxiliaryequipment, that is completely selfcontained, and that is not reliant onan A.C. supply but is directly connectable to any conventional A.C. orDC. power supply; in other words, a self-contained, universal, electricreciprocating motor that may be embodied in any desired size, atsubstantially any desired power and with substantially any desiredreciprocatory stroke and speed, and that may, for example, be madeportable and embodied in a wide variety of products, such as portablereciprocatory power tools.

It is specifically an object of this invention to provide an improvedelectromagnetic reciprocating motor including a cylinder, one or morecoils on the cylinder and an armature on the cylinder actuated uponenergization of the coil or coils, characterized in that energization ofthe coils in properly timed relation to armature reciprocation isgoverned by switching means incorporated in the motor armature.

A further object of the invention is the provision of an improvedelectromagnetic reciprocating motor as afore said including one or morecoils on the cylinder each connected to one side of either an AC. or DC.power supply and including a pair of circumferentially spaced contactsprojecting into the cylinder, the contacts of the coil or coils definingtwo separate sets of stationary contacts, and switch means on thearmature having connection to the other side of the power supply andresponsive to movement of the armature to opposite ends of the cylinderfor alternately energizing a pair of circumferentially spaced armaturecontacts that are respectively engageable with the contacts of the twostationary sets, whereby to energize the coil or coils first through oneset of contacts in the direction to move the armature to one end of thecylinder, whereupon the switch is actuated, and then to energize thecoil or coils through the other set of contacts in the oppositedirection to move the armature to the other end of the cylinder,whereupon the switch is again actuated to initiate repetition of thereciprocatory movement described.

A still further object of the invention is to embody the improved motorabove defined in a compact, economical and portable assembly forconvenient commercial and industrial use.

Other objects and advantages of the invention will become apparament inthe following detailed description.

Now, in order to acquaint those skilled in the art with the manner ofmaking and using my improved electromagnetic reciprocating motor, Ishall describe, in connection with the accompanying drawings, apreferred embodiment of the motor and the preferred manners of makingand using the same.

In the drawings:

FIGURE 1 is a vertical longitudinal section of a universalelectromagnetic reciprocating motor embodying the present invention, theView showing the armature in one end position;

FIGURE 2 is a fragmentary longitudinal section of the motor showing thearmature in its other end position; and

FIGURE 3 is an enlarged cross-sectional view of the motor takensubstantially on line 3-3 of FIGURE 1.

Referring now to the drawings, my improved motor in its preferredembodiment is comprised of a non-magnetic cylinder 10, a plurality ofelectric coils 12 surrounding said cylinder in spaced relation to oneanother and the ends of the cylinder, a permeable armature 14reciprocably mounted in the cylinder, and switch means (to be describedin detail hereinafter) mounted principally on the armature for governingenergization of the coils. The coils 12 and armature 14 are conventionalelements of both the reciprocatory electric motor and solenoid arts, andelectrical design parameters therefor may be determined from said arts.The object of the present invention is the provision of improved switchmeans for electromagnetic reciprocating motors, and the detaileddescription is therefore directed primarily to said switch means and thephysical combination thereof with the cylinder 10, the coils 12 and thearmature 14.

The cylinder 10 may be formed of any suitable nonmagnetic material,metallic or non-metallic, and may take the form of a cylinder ofcircular section (as shown herein), a square or polygonal tube, a simpleframework for guiding reciprocable movement of the armature, or thelike. Irrespective of its form, the cylinder is provided at or adjacentits ends with abutments 16 that extend into the path of reciprocablemovement of the armature for defining the end limits of armature travel.In the case of a circular cylinder as shown herein, the abutments maysuitably comprise apertured discs or washers threaded into the ends ofthe cylinder, the apertures venting air from the cylinder wherebymovement of the armature will be unimpeded. In a proper design, theabutments 16 could comprise sealed end closures and the cylinder couldcontain air, be evacuated, or be filled with a selected fluid forpurposes of governing armature movement.

The coils 12 are of conventional cylindrical or torroidal form and areconstructed in accordance with established standards of the art toproduce from the selected or available supply of electric power thedesired magnetic influence on the armature for pulling the armature intoa centered position relative to the coil. The coils are secured in anysuitable manner to the exterior surface of the cylinder. The number,size and placement of the coils are dependent upon the size and thereciprocatory stroke of the armature, and are herein shown as two innumber, namely, 12a and 12b. Each coil has three taps comprising a maintap or lead 18 (FIGURE 3) to be connected to one side of the powersupply and a pair of taps 2t) and 22 extending from opposite sides andcircumferentially spaced areas of the coil. In essence, tap 18 isconnected to or comprises one end of the wire forming the respectivecoil, and the taps 20 and 22 are connected adjacent, or togethercomprise, the other end of such wire. Each of the taps 20 and 22 of eachcoil is connected to a respective contact, which are indicated at 20aand 22a and 20b and 22b, respectively, for the two coils 12a and 12b ofthe two-coil motor illustrated herein.

Each of the contacts is disposed radially of the cylinder, the samebeing mounted on box-like structures 24 which are fixedly secured to thecoils and the cylinder. Each contact projects radially through the wallof the cylinder 10, and in the case of conductive cylinder materials isinsulated therefrom by an insulative grommet 26 held in place by aspring 28 confined between the grommet and the respective structure 24.The contacts project only a slight distance inwardly from the cylinderwall, and are preferably adjustably mounted on the structures 24 toaccommodate proper adjustment of the contacts and to compensate .forcontact wear.

The contacts 20a and 20b are aligned with one another longitudinally ofthe cylinder to define one set of longitudinally spaced stationarycontacts located to one side of their respective coils, and the contacts22a and 22b are aligned longitudinally of the cylinder incircumferentially spaced relation to the contacts 20a and 20b to definea second set of longitudinally spaced stationary contacts located to theopposite side of their respective coils. While the two sets of contactsmay be spaced any desired circumferential distance, the same have beenshown herein as spaced 180 degrees thereby to define a lower set ofcontacts Zita and 20b and upper set of contacts 22a and 22b.

The armature 14 comprises a slug of permeable material of a size andconfiguration corresponding to the interior size and configuration ofthe cylinder 10, the same in the disclosed embodiment comprising a solidcylindrical slug of iron. Mounted on or in this slug is the switch meansof the invention, the mount therefor in the preferred embodiment beingdefined by a pair of radially open longitudinally elongated slots 3% inthe peripheral wall of the armature. The two slots 30 are spacedcircumferentially from one another by the same arcuate distance (in thiscase 180 degrees) as the stationary contacts on the cylinder, wherebythe slots are aligned respectively with two sets of contacts Zita-20band 22a-22b. Both slots are lined at all but one end face thereof withinsulating material, as indicated at 32, one end face of one slot andthe other end face of the other slot being left exposed. Preferably,substantially the entire surface of the armature is encased ininsulation. The insulation may suitably be one having a low cofficientof friction, such as Teflon or Delrin, whereby to form bearing means forthe reciprocable armature and also to cushion the impact of the armatureagainst the abutments 16.

Slidably mounted for longitudinal movement in each of the slots 30 is anelongate contact bar 34 of significant mass. Each bar is shorter thanthe slot in which it is received and has freedom for endwise movement inits respective slot and is exposed at the periphery of the armature forcontacting engagement with a respective set of stationary contacts20a20b and 22a-22b. Extending through the non-insulated wall of eachslot 30 is a fixed contact 36 which is insulated from and extendsradially inwardly to the center of the armature, one of said contactsbeing located at one end of one slot and the other being located at theother end of the other slot. Upon movement of the armature toward eitherend of the cylinder, the armature and the two contacts 34 gain momentum.When the armature is suddenly stopped by engagement with an abutment 16,the contacts 34 due to their momenturn continue to move in the initialdirection, whereupon one contact 34 breaks from the adjacent contact 36and the other contact 34 makes with its contact 36, whereby to perform aswitching function at each end of the reciprocatory path of movement ofthe armature.

At its inner end, in the embodiment of the invention herein disclosed,each contact 36 is connected to the pigtail of a conductive brush 38which is spring-pressed radially outwardly at right angles to the planeof the contacts 34 and 36. The circumferential spacing of the brushes 38from the contacts 34 may, of course, be varied as desired, but it ispreferred that the two brushes lie in a common plane spacedcircumferentially from both sets of contacts. At their outer ends, thebrushes 38 project into a longtidinal groove 49 in the periphery of thearmature which groove extends throughout the full length of thearmature. The groove is intended for reception therein of a longitudinalguide block 42 which is secured to the inner wall of the cylinder andextends from adjacent one end to adjacent the other end thereof for thepurpose of slidably guiding the armature and retaining the same againstrotation, whereby the armature will be retained in the position whereinits contacts 34 are aligned with the contacts 26311401) and Z2a22b. Theguide block 42 may suitably be formed of a plastic insulating materialhaving a low coefficient of friction, for the same purposes aspreviously explained. (In non-circular cylinder configurations, theguide block would not be necessary, since the configuration of thecylinder and armature would prevent rotation of the armature.)

Fixedly mounted on the guide block 42 is an elongate conductor bar 4-4which extends into the groove 40 and is slidably engaged by the brushes38 throughout the reciprocatory path of movement of the armature. Thebar 44 in turn is adapted to be connected by way of conductive bolts 46and a tap or lead 48 to the side of the power supply opposite that towhich the taps or leads 18 are connected.

The cylinder 10, coils llZ, armature 14, abutments 16, stationarycontacts vMia-20b and 22a-22b, and longitudinally shiftable contacts 34,are, of course, properly correlated to one another to achieve theintended purposes. While the necessary correlation will be obvious tothose skilled in the art, I will describe, by way of example, thecorrelation employed in the preferred embodiment of the invention. Asshown, the coils 12 are spaced apart equal distances from one anotherand from the abutments l6, and the stationary contacts are centered insuch spaces, i.e., the contact Zita is positioned centrally in the spacebetween the left-hand abutment 16 and the left-hand coil 12a, thecontacts 201) and 22a are positioned centrally of the space between thetwo coils and the contact 22b is positioned centrally in the spacebetween the right-hand coil 12b and the right-hand abutment 16. If morethan two coils were provided, their spacing and contact arrangementswould be the same as that between the two coils illustrated. Thecylinder 10 is, of course, of a length to accommodate the aforesaidrelationship of the coils 12, the abutments 16 and the contacts Zita-20band 22a- 22b.

The armature 10 is of a length less than twice, preferably substantiallyless than twice, the spacing of the centers of the coils 12a and 12bfrom the abutments L6 adjacent thereto, and yet of a length toaccommodate, with freedom for sliding movement, contacts 34 that are ofa length only slightly less than the spacing between the contacts ofeach set mounted on the cylinder, e.g., the spacing between the contacts2% and Ziib. The contacts 34 in turn are so positioned (preferablycentered) on the armature that the distance between the trailing end ofthe contact 34 and the center of the armature is less than the distancebetween the center of the coil and its contact-s.

With the defined structural arrangement, and with the armaturepositioned as shown in FIGURE 1 and the two power supply leads 18 and 43connected to opposite sides of a suitable power source, either AC. orD.C., the operation of the motor is as follows: The left-hand coil 12ais initially energized by virtue of current flow via the lead 48, thebar 44, the left-hand brush 38 and contact 36, the lower slidablecontact 34, the contact 29a, the tap 2d, the windings of the coil andthe lead 13. The coil 12a thus produces a magnetic field, causing thearmature 14- to move to the right toward a centered position relative tothe coil 12a. However, shortly before the armature reaches such centeredposition, the lower contact 34 'disengages from the contact 20a wherebythe coil 12a is de-energized and the momentum of the armature causes itto slide by the coil 12a until the lead end of the,

lower contact 34 engages the contact 2012 of the coil 12b. The coil 12bthus becomes energized and exerts a magnetic attraction for thearmature, so that the armature (the lead end of which is now in thefield of influence of coil 12b) is drawn to the right toward a centeredposition relative to the coil 12b. Again, however, the lower contact 34disengages from the contact 20b so that the armature, due to itsmomentum, slides past the coil 12b toward the right-hand abutment 16.During this movement, the upper contact 34 and the contacts 22a and 22bare ineffective since the upper contact 34 is not engaged with and thusis not energized via the upper right-hand supply contact .36.

When the right-hand end of the armature 14 engages the right-handabutment 16, the armature is abruptly stopped. However, the contact bars34 due to their momentum continue to move to the right, whereby thelower left-hand switch means 34-36 is opened and the upper right-handswitch means 34-36 is closed, as shown in FIGURE 2. Thus, the lowercontacts 20a, Nb and 34 are rendered ineffective but the circuit is nowclosed via the upper contacts V334- and 22b through the coil 12!), againto energize this coil. Consequently, the coil 12b again exerts acentering force relative to the armature, now causing the armature(which has glided past center position) to move toward the left. Beforecentered position is reached, the upper contact 34 breaks from thecontact 22b whereby the armature slides past the coil 1215 until theupper contact 34 engages the contact 22a to energize coil 12a and pullthe armature further to the left. Before the armature reaches centerposition relative to the coil 12a, the upper contact 34 disengages fromthe contact 22a whereupon the center of the armature moves past thecenter of the coil 12a. When the armature strikes the left-hand abutment16, the impact or momentum responsive contact bars 34 shift to the left,whereby the apparatus is reconditioned, as shown in FIGURE 1, for thecycle of operation above described.

From the foregoing, it will be obvious to those skilled in the art thatthe motor of the present invention may be comprised of substantially anydesired number of ar mature actuating coils, even a single coil disposedsubstantially centrally of a relatively short cylinder 10.

The present invention is thus seen to provide an extremely economicaland compact universal electromagnetic reciprocating motor. The motor maybe fabricated in substantially any size, for substantially anyhorsepower output and/or for substantially any reciprocatory stroke andspeed. For example, the motor may be made of about hand size foroperation of portable reciprocating power tools, such as saber saws.Accordingly, the objects and advantages of the invention have been shownherein to be attained in a convenient, economical and practical manner.

While I have shown and described what I regard to be the preferredembodiment of my invention, it will be appreciated that various changes,rearrangements and modifications may be made therein without departingfrom the scope of the invention, as defined by the appended claims.

I claim:

1. An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutments adjacent its ends, a plurality of electriccoils arrayed in longitudinally spaced relation to one another alongsaid cylinder, each coil being connected to one side of an electricpower source and including a pair of contacts extending through saidcylinder in circumferentially spaced relation to one another,corresponding contacts of the coils defining two sets of longitudinallyspaced contacts, a magnetic armature slidably mounted in said cylinder,switch means on said armature responsive to engagement of the armaturewith said abutments and including a pair of alternately energizedcontacts circumferentially spaced from one another and respectivelyengageable with the contacts of said two sets, a power supply elementextending from ad- 6 jacent one end to adjacent the other end of saidcylinder and connected to the other side of the electric power source,and conductor means connecting said supply element to said switch means.

2. An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutments adjacent its ends, at least one electric coilmounted on said cylinder in spaced relation to its ends, said coil beingconnected to one side of an electric power source, a pair of contactsconnected to said coil and extending through said cylinder incircumferentially spaced relation to one another, a magnetic armatureslidably butnon-rotatably mounted in said cylinder, switch means on saidarmature responsive to engagement of the armature with said abutmentsand including a pair of alternately energized contacts circumferentiallyspaced from one another and aligned respectively with said coilcontacts, a power supply bar extending longitudinally of said cylinderand connected to the other side of the electric power source, andconductor means on said armature connected to said switch means andslidably engaging said bar for supply of electric power alternately tothe contacts on said armature.

3. An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutment means adjacent its ends, at least one electriccoil on said cylinder adjacent but spaced from one of its ends, saidcoil being connected to one side of an electric power supply andincluding a pair of contacts projecting through said cylinder incircumferentially spaced relation to one another, a magnetic armaturereciprocably mounted in said cylinder, switch means on said armatureresponsive to engagement of the armature with said abutments andincluding a pair of alternately energized circumferentially spacedcontacts on the surface of the armature engageable respectively withsaid coil contacts, a power supply bar extending from adjacent one endto adjacent the other end of said cylinder and connected to the otherside of the electric power supply, and conductor means on said armatureslidably engaging said bar and connected to said switch means foralternate energization of the contacts on said armature, said switchmeans upon engagement of said armature with the abutment at the one endof said cylinder coupling one armature contact with said bar andde-energizing the other armature contact, said armature being of alength less than twice the spacing between the center of said coil andthe adjacent end of the cylinder, said one armature contact beingaligned with and engaging one contact of said coil when the armature isin said one end of said cylinder for energizing said coil to initiatemovement of said armature toward the other end of said cylinder, saidone armature contact and said one coil contact having a contact lengthsufficient to maintain said coil energized until the center of thearmature approaches but has not reached the center of said coil.

4. An electromagnetic reciprocating motor as set forth in claim 3,including a plurality of coils arrayed in longitudinally spaced relationalong said cylinder, each coil being connected to one side of theelectric power supply and including a pair of contacts projecting intosaid cylinder and aligned in respective sets with the contacts of thefirst-named coil, the contact of each succeeding coil in the directionof armature movement corresponding to said one contact of thefirst-named coil being spaced from said one contact of the precedingcoil a suflicient distance that said one armature contact disengagesfrom said one contact of the preceding coil before engaging the onecontact of the next succeeding coil, said one armature contact and saidone contact of each succeeding coil having a contact length suflicientto maintain the respective succeeding coil energized from substantiallythe time the leading end of said armature enters the field of influenceof said succeeding coil until the center of the armature approaches buthas not reached the center of the succeeding coil, said other armaturecontact being aligned with and engaging the other contact of the coiladjacent said other end of said cylinder when the armature is in saidother end of said cylinder and has engaged the abutment at said otherend of said cylinder for energizing the lastnamed coil to initiatemovement of said armature toward said one end of said cylinder, saidother armature contact, said other contact of said last-named coil andthe other contacts of the succeeding coils in the direction from saidother end of said cylinder toward said one end of said cylinder havingthe same relationship to one another a have said one armature contact,said one contact of said first-named coil and said one contact of thesucceeding coils in the direction from said one end of said cylindertoward said other end of said cylinder.

5. An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutments adjacent its ends, a plurality of electriccoils arrayed in longitudinally spaced relation to one another alongsaid cylinder, each coil being connected to one side of an electricpower supply and including a pair of contacts extending through saidcylinder in circumferentially spaced relation to one another to oppositesides of the respective coil, corresponding contacts of the coilsdefining two sets of longitudinally spaced contacts, a magnetic armaturereciprocably mounted in said cylinder, switch means on said armatureresponsive to engagement of the armature with said abutments andincluding a pair of circumterentially spaced alternately energizedelongated contacts of a length less than the spacing between thecontacts of each of said sets and respectively engageable sequentiallywith the contacts of the two sets, and means connecting said switchmeans to the other side of the electric power supply.

6. An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutments adjacent its ends, a plurality of electriccoils arrayed in longitudinally spaced relation to one another alongsaid cylinder, each coil being connected to one side of an electricpower supply and including a pair of contacts extending through saidcylinder in circu'mferentially spaced relation to one another toopposite sides of the respective coil, corresponding contacts of thecoils defining two sets of longitudinally spaced contacts, a magneticarmature reciprocably mounted in said cylinder, switch means on saidarmature responsive to engagement of the armature with said abutmentsand including a pair of circumferentially spaced alternately energizedelongated contacts of a length less than the spacing between thecon-tacts of each of said sets and respectively engageable sequentiallywith the contacts of the two sets, a power supply element extending fromadjacent one end to adjacent the other end of said cylinder andconnected to the other side of the electric power supply, and conductormeans connecting said element to said switch means.

'7. An electromagnetic reciprocating motor comprising a non-magneticcylinder having internal abutments adjacent its ends, a plurality ofelectric coils surrounding said cylinder in equally spaced relation toone another, each coil being connected to one side of an electric powersupply and including a pair of contacts extending through said cylinderin circumferentially spaced relation to one another to opposite sides ofthe respective coil, corresponding contacts of the coils being alignedwith one another longitudinally of said cylinder and defining two setsof equally spaced contacts, a magnetic armature reciprocably butnon-rotatably mounted in said cylinder between said abutments, switchmeans on said armature responsive to engagement of the armature withsaid abutments and including a pair of circumferentially spacedalternately energized contacts respectively aligned and engagea-blesequentially with the contacts of the two sets, the contacts on thearmature being elongated but of a length less than the spacing betweenthe contacts of each Set, and means connecting said switch means to theother side of the electric power supply.

8. An electromagnetic reciprocating motor comprising a non-magneticcylinder having internal abutments adjacent its ends, a plurality ofelectric coils surrounding said cylinder in equally spaced relation toone another, each coil being connected to one side of an electric powersupply and including a pair of contacts extending through said cylinderin circumferentially spaced relation to one another to opposite sides ofthe respective coil, corresponding contacts being aligned with oneanother longitudinally of said cylinder and defining two sets of equallyspaced contacts, a magnetic armature reciprocably mounted in saidcylinder between said abutments, switch means on said armatureresponsive to engagement of the armature with said abutments andincluding a pair of circumferentially spaced alternately energizedcontacts respectively aligned and engageable sequentially with thecontacts of the two sets, the contacts on the armature being elongatedbut of a length less than the spacing between the contacts of each set,a power supply bar on the internal wall of said cylinder extendinglongitudinally from adjacent one end to adjacent the other end of saidcylinder and connected to the other side of the electric power supply, alongitudinal groove in said armature spaced circumterentially from thecontacts thereon and slidably engaging said bar for retaining saidarmature against rotation, and brush means in said groove slidablyengaging said bar and connected to said switch means.

9. An electromagnetic reciprocating motor comprising a nonmagneticcylinder having abutments adjacent its ends, at least one electric coilon said cylinder, said coil being connected to one side of an electricpower supply and including a pair of contacts extending through saidcylinder in circumferentially spaced relation to one another to oppositesides of the coil, a magnetic armature reciprocably mounted in saidcylinder, switch means on said armature comprising a pair of elongatecontacts slidably mounted on said armature in circumferentially spacedrelation to one another for engagement respectively with the contacts ofsaid coil, a fixed contact on said armature adjacent one end of one ofsaid elongate contacts and a fixed contact on said armature adjacent theother end of the other of said elongate contacts, said elongate contactsbeing of significant mass for movement relative to said armature uponimpact of the armature against said abutments for performing switchingfunctions relative to said fixed contacts, and means connecting saidfixed con tacts to the other side of the electric power supply.

It). An electromagnetic reciprocating motor comprising a non-magneticcylinder having abutments adjacent its ends, at least one electric coilon said cylinder, said coil being connected to one side of an electricpower supply and including a pair of contacts extending through saidcylinder in circumferentially spaced relation to one another to oppositesides of the coil, a magnetic armature reciprocably mounted in saidcylinder, said armature having a pair of circumferentially spacedlongitudinally extending grooves in its side wall respectively alignedwith the contacts of said coil, a contact fixed in one end of one grooveand a contact fixed in the other end of the other groove, a pair ofelongate contacts of significant mass slidably mounted in said grovesfor movement into and out of engagement with the respective fixedcontacts upon impact of said armature against said abutments, leads fromsaid fixed contacts extending radially into the interior of saidarmature, brush means connected to said leads and extending to aradially exposed portion of the armature spaced circumferentially fromsaid grooves, and a power supply bar extending longitudinally of saidcylinder for slida'ble engagement by said brush means, said bar beingconnected to the other side of the electric power supply.

References Cited by the Examiner UNITED STATES PATENTS 3,135,880 6/1964Olson et a1. 31014 ORIS L. RADER, Primary Examiner.

1. AN ELECTROMAGNETIC RECIPROCATING MOTOR COMPRISING A NON-MAGNETICCYLINDER HAVING ABUTMENTS ADJACENT ITS ENDS, A PLURALITY OF ELECTRICCOILS ARRAYED IN LONGITUDINALLY SPACED RELATION TO ONE ANOTHER ALONGSAID CYLINDER, EACH COIL BEING CONNECTED TO ONE SIDE OF AN ELECTRICPOWER SOURCE AND INCLUDING A PAIR OF CONTACTS EXTENDING THROUGH SAIDCYLINDER IN CIRCUMFERENTIALLY SPACED RELATION TO ONE ANOTHER,CORRESPONDING CONTACTS OF THE COILS DEFINING TWO SETS OF LONGITUDINALLYSPACED CONTACTS, A MAGNETIC ARMATURE SLIDABLY MOUNTED IN SAID CYLINDER,SWITCH MEANS ON SAID ARMATURE RESPONSIVE TO ENGAGEMENT OF THE ARMATUREWITH SAID ABUTMENTS AND INCLUDING A PAIR OF ALTERNATELY ENERGIZEDCONTACTS CIRCUMFERENTIALLY SPACED FROM ONE ANOTHER AND RESPECTIVELYENGAGEABLE WITH THE CONTACTS OF SAID TWO SETS, A POWER SUPPLY ELEMENTEXTENDING FROM ADJACENT ONE END TO ADJACENT THE OTHER END OF SAIDCYLINDER AND CONNECTED TO THE OTHER SIDE OF THE ELECTRIC POWER SOURCE,AND CONDUCTOR MEANS CONNECTING SAID SUPPLY ELEMENT TO SAID SWITCH MEANS.